It is known to deposit diamond-like carbon (DLC) coatings on a substrate. Unfortunately, DLC becomes dark in color and absorbs visible light rays at high thicknesses. DLC may even absorb some visible light at small thicknesses.
There exists a need in the art to coat articles such as vehicle windows/windshields, architectural glass, etc. with DLC in order to make such articles more scratch resistant and durable. However, such articles may often be used in environments (e.g., vehicle windshields, vehicle windows, etc.) where high visible light transmission (i.e., low visible light reflection and/or absorption) is desirable. Thus, there exists a need in the art to provide a coated article including at least one DLC inclusive layer(s) thereon for durability purposes which at the same time can experience sufficiently high visible light transmittance and/or low visible light reflectance if same is desired.
Certain of the aforesaid parent applications discuss the use of a TMS gas to form a DLC inclusive layer disposed between a glass substrate and another DLC inclusive layer deposited via at least acetylene gas. While such articles have many desirable characteristics and function very well, the use of TMS gas to form the layer between the other DLC inclusive layer and a glass substrate has been found to lead to a resulting article experiencing more visible light reflection than would otherwise be desired. The refractive index "n" of glass is about 1.57, while the refractive index "n" of DLC deposited via acetylene gas is about 2.0 in the visible range. A layer deposited using TMS gas typically has a refractive index "n" of about 1.9 to 2.0. As a result of the rather high refractive index "n" of such a TMS layer, the resulting article tends to experience more visible light reflection than would otherwise be desired in certain circumstances.
In view of the above, it is apparent that there exists a need in the art for a coated article including at least one DLC inclusive layer that has good visible transmission characteristics, and a corresponding method of making the same. There also exists a need in the art for a layer which can be deposited directly between a glass substrate and a DLC inclusive layer that more closely matches or couples the respective refractive indices of the glass and DLC in order to reduce visible reflection(s) off of the resulting coated article. Thus, there further exists a need in the art for a layer having a refractive index "n" of from about 1.4 to 2.0 (more preferably from about 1.5 to 1.8) that is compatible with DLC and glass which may be disposed between a DLC inclusive layer and a glass substrate, which can limit visible light reflection off of a resulting coated article and simultaneously can provide a good bond between the DLC and glass.
It has also been found that under certain circumstances hydrophobic layers such as fluoro-alkyl silane (FAS) inclusive layers have trouble bonding directly to hard DLC inclusive layers deposited using acetylene gas. Thus, there also exists a need in the art for a DLC inclusive hydrophobic coating system including a primer layer for improving bonding between an overlying hydrophobic layer and an underlying DLC inclusive layer.
It is a purpose of different embodiments of this invention to fulfill any and/or all of the above described needs in the art, and/or other needs which will become apparent to the skilled artisan once given the following disclosure.